Drupal Commerce documentation focuses on basic configuration steps for beginners, architectural documentation for intermediate users wondering how all the components work together, and technical documentation for developers. Documentation is under constant development by community contributors and is therefore subject to change.
In addition to on-site documentation, we will be linking to various training opportunities, books, and additional resources for learning Drupal Commerce. The closest opportunity will be next week's DrupalCon Chicago, so be sure to take advantage of the relevant training and sessions while you're there!